I want to send a mail to a mailing list every period of time (like every 40min or hour) with java on a unix server.
I'd like any code or tutorial to be able to do this.
Sending a mail to a mailing list does not differ from sending a regular mail. The simplest way is to use commons-email. Check its examples.
JavaMail is the usual approach for this. You will need a SMTP-server for JavaMail to connect to.
If it is not necessary to USE SMTP - java mail enough Simple example http://pastebin.com/z4YxKFe6